colour.HelmholtzKohlrausch_effect_object_Nayatani1997#

colour.HelmholtzKohlrausch_effect_object_Nayatani1997(uv: ArrayLike, uv_c: ArrayLike, L_a: FloatingOrArrayLike, method: Union[Literal['VAC', 'VCC'], str] = 'VCC') FloatingOrNDArray[source]#

Return the HKE value for object colours using Nayatani (1997) method.

Parameters:
  • uv (ArrayLike) – CIE uv chromaticity coordinates of samples.

  • uv_c (ArrayLike) – CIE uv chromaticity coordinates of reference white.

  • L_a (FloatingOrArrayLike) – Adapting luminance in \(cd/m^2\).

  • method (Union[Literal['VAC', 'VCC'], str]) – Which estimation method to use, VCC or VAC.

Returns:

Luminance factor (\(\Gamma\)) value(s) computed with Nayatani object colour estimation method.

Return type:

numpy.floating or numpy.ndarray

References

[Nay97]

Examples

>>> import colour
>>> white = colour.xy_to_Luv_uv(colour.temperature.CCT_to_xy_CIE_D(6504))
>>> colours = colour.XYZ_to_xy(
...     [colour.wavelength_to_XYZ(430 + i * 50) for i in range(5)]
... )
>>> L_adapting = 65
>>> HelmholtzKohlrausch_effect_object_Nayatani1997(  
...     colour.xy_to_Luv_uv(colours), white, L_adapting
... )
array([ 2.2468383...,  1.4619799...,  1.1801658...,  0.9031318...,  1.7999376...])